Graphite mold having resin-bonded sand portions



Much 7 R. E. MERRICK ETAL 3,498,366 GRAPHITE now HAVING RESIN-BONDED SAND Pon'rxous Filed a 5. 1966 "United States Patent US. Cl. 164-368 4 Claims ABSTRACT OF THE DISCLOSURE A graphite mold for casting ferrous articles having a portion thereof formed of resin-bonded sand to provide improved surface conditions of the cast articles and to produce articles having chilled wear surfaces at the graphite contacting portions thereof and softer surfaces at the sand contacting portions thereof.

This invention relates to molds suitable for use in forming metal castings and more particularly to molds adapted for use with pressure pouring apparatus in which molten metal is forced upwardly under pressure through an ingate and into the bottom of a mold cavity.

Such molds have been proposed and are presently being used commercially to produce cast iron and steel wheels. These molds are also used to produce cast iron mullers. Cast wheels and mullers have been successfully manufactured in existing mold equipment. However, in the production of cast iron mullers with present mold equipment certain drawbacks have been found to exist. The plate portions of the mullers produced in existing molds require additional finishing operations to provide the desired surface finish. In addition, gas holes may be found in the muller, which must be removed.

It is, therefore, an object of the present invention to provide a new and improved mold apparatus for use in pressure pouring cast iron and steel articles.

Another object of this invention is to provide a mold for pressure pouring cast iron articles, which articles have improved surface characteristics.

A further object of this invention is to provide mold equipment for pressure pouring cast iron mullers.

Another object of this invention is to provide a mold for cast iron mullers from a single iron composition, wherein the muller is provided with a chilled tread wearing surface and a machinable plate portion.

FIGURE 1 is an elevational view in cross section of mold apparatus according to this invention; and

FIGURE 2 is a cross-sectional view of the mold apparatus taken along the plane of line 22 of FIGURE 1.

Referring now to the drawing, reference numeral denotes a mold which comprises a graphite cope 12 and a graphite drag 14 which define therebetween a casting cavity 16 suitable for casting iron mullers or other cast iron or steel articles.

The drag 14 is provided with an ingate 18 through which molten metal is forced upwardly under pressure into the bottom of the hub portion of the casting cavity 16 in the conventional pressure pouring procedure. The ingate 18 is coaxial with the cavity and it is formed at its upper end with a frustoconical seat 20 for engagement with a stopper 22. The stopper 22 comprises a stem 24 extending from outside of the cope 12 and terminating at its lower end in a stopper portion 26 having a frustoconical surface 28 for engagement with the frustoconical surface 20 of the ingate. The stopper 22 is utilized to terminate flow of molten metal into the casting cavity 16 and to provide means for removing the casting from the mold after at least partial solidification.

The stopper 22 is provided with a cylindrical resinbonded sand portion 126 which rests upon the stopper portion 26. This cylindrical portion 126 is retained in place by a washer 128.

The cope 12 is formed with coaxial bores 30 and 32 which merge with an intermediate annular downwardly facing shoulder 34 to receive a porous resin-bonded sand head 36 having a concave lower surface 38 to define with the bore 32 a hub riser cavity 40. It will be noted that the lower end of the sand head 38 is spaced up: wardly from the lower end 42 of the bore 32 to leave a cylindrical graphite wall below the head to serve as a freeze-off to permit quick pickup of the cast muller without disengaging the stopper stem 24 from the muller. Preferably a metallic washer 44 is embedded within the lower end of the sand head 38. The washer 44 and head 38 are provided with coaxial openings 46 and 48, respectively, to snugly receive therein the stopper stem 24.

The upper portion of the cope 12 is provided with a third bore 50 which is coaxial with bores 32 and 30 and is adapted to snugly receive a metallic guide spider 52 having concentric rings 54 and 56 interconnected by radial ribs 58. The inner ring 56 is formed with a bore 60 terminating at its lower end in a shoulder 62 to receive therein the lower end of a fiberboard tube 64. The stopper stem 24 extends upwardly through the tube 64 and is detachably engaged against movement relative thereto by means of a staple 66 which serves to clamp opposite sides of the tube against the stem 24 when the stopper 22 is held in its raised and open position. Means, not shown, are provided on the upper end of the stopper stem 24 to engage a lifting device which may be utilized to remove the casting from the mold cavity 16.

The cope 12 is provided with a plurality of circumferentially spaced gas ports 68 which extend axially therethrough and are disposed inwardly and radially from the tread portion of the casting cavity 16. Three of the gas holes 68 are provided with a press-in steel sleeve 70. These holes are positioned 120 from each other. In radial alignment with the gas holes 68 is a riser bore 72. The riser bore 72 is provided with a cylindrically shaped liner 74 formed of resin-bonded sand.

The drag 14 is provided with a plurality of circumferentially spaced vent holes 76. The vent holes 76 are spaced outwardly from the ingate 18 and inwardly from the tread portion of the casting cavity 16. In the illustrated embodiment they are in vertical alignment with gas holes 68. This is the preferred embodiment. Three equally spaced vent holes 76 are provided with enlarged portions 78 at their upper ends to receive therein a chaplet 80, the function of which will be explained hereinafter. The upper surface of the drag 14, which is that portion which defines the plate portion of the cast muller, is machined to provide a recess 82. This recess 82 surrounds the ingate 18 and extends radially outwardly therefrom into close proximity to the tread forming portion 84 of the drag 14. The recess 82 is provided with two circumferential grooves 86 and 88 to anchor the sand 90 in the recess 82. These grooves 86 and 88 and the recess 82 are filled with resin-bonded sand 90 which sand forms the plate casting portion 92 of the drag 14.

The cope 12 is provided with a recess 94 similar to the recess 82 of the drag 14. The recess 94 extends radially outwardly from close proximity to the lower end 42 of the bore 32 to close proximity to the thread forming portion 95 of the cope 12. Circumferential grooves 96 and 98 are provided to aid in anchoring the resin-bonded sand 100, which is placed in the recess 94 and grooves 96 and 98. The sand liner 100 is provided with a riser sprue opening 102 in vertical alignment with the riser opening 72. The sand liner 100 is also provided with three openings 104 in vertical alignment with the three steel sleeves 70 which openings'104 areadapted'to' receive therein a core leg 106, the function of which will be explained hereinafter. v I

A pan core 108 is centered with respect to the cavity 16 of the mold 10. The pan core 108 is constructed of oil-bonded sand and baked in a core oven in a conventional manner and is tire-shaped in configuration, which is the conventional construction for such an item. It is provided with a continuous circular vent 110 in the center thereof, which vent is in open communication with three vertical vent passages 112, only one of which is shown in FIGURE 1. The other two are 120 apart from each other and the vent passage as shown. The vent passages 112 are in open communication with an opening 114 in the upper surface 116 of the pan core 108. These openings 114 are adapted to receive therein the lower portion of the core legs 106 which are provided with a vertical opening 118 in order that gases generated within the pan core may escape through the steel sleeves 70. The undersurface 120 of the pin core 108 provided with a plurality of openings 122 to receive therein the upper portion 124 of the chaplets 80. The chaplets 80 and core legs 106 serve to position the pan core 108 within the mold cavity 16.

In operation, molten metal in the conventional pressure pouring technique is forced upwardly through the ingate 18 in to the mold cavity 16 until the cavity is filled with molten metal. The stopper 22 is then moved into position with its conical surface 28 abutting the conical surface 20 of the ingate, thereby preventing the metal within the mold from returning to the ladle through the ingate 18 and also preventing additional metal from flowing into the mold cavity. The gases generated within the cavity 16 during the pouring and solidification of the casting escape through the riser 72. The gases generated within the pan core 108 ascape through the three steel sleeves 70. The remaining openings 68 and 76 are utilized to permit escape of gases from resin-bond sand 90 and 100. The gases are then burned off in the conventional manner.

After at least partial solidification of the muller, the

cope 12 is lifted off of the drag 14 in the conventional manner. The muller may then be removed by lifting the stopper 22. Thereafter the muller is cooled in the conventional manner.

It has been found that by casting mullers utilizing the mold of this invention having the plate surface of the mold formed substantially of resin-bonded sand, the mullers are superior in quality to those obtained in conventional sand molds. While the preferred embodiment of this invention has been described herein before, it should be understood that various modifications may be made in the same without departing from the spirit and scope of the following claims.

We claim:

1. A mold for casting ferrous articles comprising a cope and a drag defining therebetween a casting cavity, a riser cavity in said cope, a gate in said drag, said drag and cope having the plate forming portions thereof formed of resin-bonded sand, and the remainder of the molding portions of said cope and drag being formed of graphite.

2. A mold according to claim 1 wherein said cope and drag are provided with a plurality of gas venting passages.

3. A mold according .to claim 2 wherein said gas venting passages are arranged in a circle and are equally spaced from adjacent passages.

4. A mold according to claim 1 wherein a sand core is positioned within said cavity and spaced from said plate forming and molding portions.

References Cited UNITED STATES PATENTS 1,943,434 1/1934 Hemstead et al. 24956 X 2,838,816 6/1958 Strorn 24956 3,302,919 2/1967 Beetle et al. 164-340 X 2,765,505 10/1956 Sylvester 16427 2,886,865 5/1959 Leisk 16422 J. SPENCER OVERHOLSER, Primary Examiner US. Cl. X.R. 164-125 

